Process of producing chlorpicrin



30 and findings are applicable'to other compounds tion.

Patented 7 Apr. 1935 1 ?11 39 i .7 rnooEss or PRODUCING :CI'ILORPICRINT a WilliamD. Rama, 1ittsbur,' Califal'a ssignor to Great Western'Electro-(Jhemical company, San Francisco, Califaa corporation of Californi a "No Drawing. 'Application Ji s.2.s, .19a,s= :1 Serial No. 619;354 moraine. .(ci; 260 i44)' This invention relates" to the formation: of In the intermediate cases (Eqs. 2, 3 and 4), the products by the chlorination of nitro compounds pH is such that a certain amount of hypochlo and particularly to the 'manufacture of chlorrous acid is present and the'maximumyields picrin by chlorinationofnitrocompounds. were then-obtained. zWhen approximately "two 5 It is known that chlorpicrin' can be made-by parts of hypochlorous acid to one of hypochlo- 5v reacting picricacid with bleachin'gpowder and rite- (Eq. 3) were present, the maximum yields by the reaction between calcium picrate "and were obtained although when the ratio wassrecalcium-hypochlo-rite. Among the studies made versed (Eq. 4), the yields were nearly as high of the last reaction are statements to the efiect and less foaming occurred under the more alka- '10 that an excess of lime has no bad efiect on the line condition; From Equation 5-the effect of 10.

yield of chlorpicrin when the calcium picrate excess hypochlorit'e' can be seenthe formation and hyprochlorite are reacted. I have found that of alkali which raises the pH and makes the/soluat best this statement is only partially'correct and tion too alkaline to secure-the maximum yield.

that beyond certainlimits, excess lime hada very The amount of alkali should be such-that hyobjectionable effect. Because of the limitedsolupochlorous acid exists and the final pH of the 15 bility of lime only a; relatively small lime excess 501mm,: after reaction, is substantially that of is efiective to reduce the yield of 'chlorpicrin. the hypochlorous acid. If the pH iseither higher This Ihave determined is because of the effect or lower than the pH of hypochlorous acid, the of the alkali present on the pH value of the'sblu yield affected. Obviously, the formation of a I tion. I have discovered, among other things'havstrong acid-(Eq. 1) or alkali (Eq. 5) affects the 20 ing to do with this invention, that the pH value pI-I materially and these conditions should be of the solutionis best maintained within certain avoided to get maximum yields. 1 1 limits and thatwhen these limits, which in some r In the case. .of chlorinating aliphatic nitro cases are, relatively narrow, are exceeded, the compounds, the observation of pH control ismuch yield is deleteriously afiected.- a

My invention is probably best understood by compounds; .Thus,. substantially quantitative considering certain details of the manufacture yields have been obtained upon chlorinating. niof chlorpicrin from substituted phenols, particutromethane by observing the restrictionsI have larly sodium pic although t e p a ation mentionedrelative to the pH value of thesolul i and picric acid 'sa1tsthe calciumand potassium '(6) -HsCNO-| 3H0Cl CCl3NOz+3H2O salts, as well asto llhQEtCjld-ftl'ltlf'tt) reactions with k7).- C O+2HQC +N I other hypochlorites. i i ,CChNO OH 2H0 The invention is applicable to the'production 5 :1 1 1 I, 2 of chlorpicrindromother-nitro compounds and (8) H3CN0+2NaOCl+HOCl 35 1 to the chlorination of nitrocompoundsgenerally. I CCl3N0z+2NaOI-I+H2O Thus, I have 'successfully produced chlorpicrin H I from aromatic nitro compounds" as well 1 as ali- 2 E NQHN QC QQ N-W phatic nitro compoundsand'havesecured higher From the above reactions, it is apparent that, 40 yields, by means of the present invention, on inthe chlorinationbfnitm methane, hypochlo- 40 chlorinating nitro hydrocarbon compounds gen rous'acidfgives 'the correct chlorinating. condi- 1 erally. i tions. The presence of free chlorine causes the The following equations express various *obliberation of acid and the pr n O hypochlvserved experimental facts. rites causes the liberationofalkali; Maximum (1) CeHz(NO2)sONa-+11HOC1 i b i' fi f 'f i f i 3CC13NO SE20 +3002 +Na'C1+HC1 hypoc orous am as e o y c orma mg agen g the pH being about 6. In practically all other (2) C6H2(NO2) aONa+10HOCl+NaOC1 cases studied, the maximum yields were obtained a 3CCL3NO2+6H2O+3CO2+2NaCl with mixtures of hypochlorous acid and a hypo r p chlorite, the pH from 5 to 9, preferably not much 50 (3) g g over 8. The basic requirement is, however, the

l 3 same in all cases, namely that the pH shall re- (4) CeH2(NO2)aONa+4HOCl+7NaOClmain at all times in the range of hypochlorous 3CC13NOz+3H2O+3NagCO3+2NaC1 acid and, preferably, at the pH of the acid.

C6H2(NO2)3ONa+11NaOC1+H2O+ The mtro methane canVbe prepared in various 7 ways as by the reaction between chloracetic acid 3CC13NO2+3Na2CO3+4NaOH+2NaC1 and sodium nitrite. The nitro methane can be When hypochlorous acid alone is used (Eq. 1), distilled directly into a hypochlorous acid solution hydrochloric acid is liberated, while when hypoor the chlorination with the acid conducted in chlorite alone is used (Eq. 5), alkali is liberated. thevessel where the nitro methane was formed. 50

more critical than in the casev of aromatic nitro 2 5 The following examples are illustrative of how my invention has been successfully practised.

. V Example 1 v l lbs. of picric acid and 8 lbs. of Ca(OH)2 were mixed with 10 gallons of waterin an auto-' clave. the autoclave in the form of a dilute solution of calcium hypochlorite and hypochlorous acid, one third of the chlorine being present 'as hypochlorous acid so that there were two parts of hypochlorite to one of'the acid. The was agitated at 20 C. for one hour. Steam was then admitted and the chlorpicrin distilledofi. Yield of chlorpicrin-87 lbs.

i I Example 2 i A hypochlorous acid solution was prepared by passing l'lbs. of chlorine into an agitated and cooled suspension of finely dividedCaCOa in "water. 33 lbs. of nitromethane were then added. The: temperature was kept below 20 C. during theireaction period. After twenty minutes, the reaction mixture was heated to boiling and the chlorpicrin distilled off. The yield of chlorpicrin-89 lbs.was practically quantitative.

From the foregoing I believe it will be apparent that I have disclosed a process whereby'chlorlnation of nitro compounds can be conducted to secure maximum product yields consistently by observation of the optimum pH for a given set of reacting conditions and components. The optimum ratio :ofhypochlorous acid to hypochlorite can be readily determined for nitro' compounds other thanpicric acidor its'salts and the maximum yields thereby secured I claim:

1. That step ina chlorination process to form chlorpicrin which consists conducting said chlorination process with a-chlorinating agent whose principal. effective constituent is hypo-' chlorous acid. Q

2. That step ina chlorination process to form chlorpicrin which consists in conducting .said chlorination process with a chlorinating agent consisting. substantially oflhypochlorous acid.

3. That step in a chlorination process to form chlorpicrin which consists in conducting said chlorination process with hypochlorous acid as the chlorinating agent. 7 r 1 4. That "step in .thejprocess of chlorinating a solution to form chlorpicrin therein which consists in chlorinating with a chlorinating agent consisting substantially *of hypochlorous acid.

5. 'Ihe'process: .of forming. chlorpicrin which comprises chlorinating nitro-methane withliypochlorous acid. 1 I

6. The process of forming chlorpicrin which comprises chlorinating nitro-methane with a chlorinating agent consisting mainlyof hypo-'- chlorous acid.

150 lbs. of chlorine'werethen'added'to 7. That step in the process of chlorinating a solution to form chlorpicrin therein which consists in chlorinating with; a chlorinating agent comprisinghypochlorous acid and a hypochlorite.

8. That step in the process of chlorinating a solution to form chlorpicrin therein which consists in chlorinating with a chlorinating agent comprising hypochlorous acid and a hypochlo-rite,

the pH of said solution being substantially that of hypochlorous acid.

9. That step in the process of chlorinating a solution to form chlorpicrin therein which consists in chlorinating with a chlorinating agent comprising hypochlorous acid and a hypochlorite, the proportion of hypochlorous acid and hypochlorite being such that the pH is substantially maintained in the pH range of hypochlorous acid as the reactionprocee v 10. That step in a chlorination processto form solution buffered to maintain a substantially constant pH value favorable to .the existence of hypochlorous acid at about 6 and below '7.

13. That step in achlorination process .to form chlorpicrin which consists in chlorinating in a solution buffered to maintain a substantially constant pH value favorable to the existence of hypog chlorous acid between 5 and 9 and at a temperature of'about 20 C. p I V I r 14. That step inthechlorination-process to form chlorpicrin which consists in chlorinating in a solution buifered to maintain a substantially constant pH value on theacid side favorable to the existence of hypochlorous acid. 7 7 7 15. That step in a chlorination process to form chlorpicrin which consists'in chlorinating nitromethane to chlorpicrin in .a solution buffered :to maintain a substantially constant pI-I; value pm the acid side favorable to the existence ofhypochlorous acid. r I V v g V 16.. -That step. in achlorination process to form chlorpicrin which consistsin chlorinating nitro- 

